title: High-order nonlinear Schrödinger equation and weak-light superluminal solitons in active Raman gain media with two control fields.
abstract: We propose a scheme to generate superluminal optical solitons in a four-level atomic system with two control fields via an active Raman gain. We derive a modified nonlinear Schrödinger equation with high-order corrections contributed from linear and differential absorption, nonlinear dispersion, and delay response of nonlinear refractive index of the system. We predict various optical solitons in different regimes of system parameters, and show that these optical solitons have superluminal propagating velocity and very low generation power.
authors.affiliation: Department of Physics, East China Normal University, Shanghai 200062, China.
authors.forename: Chengjie
authors.initials: C
authors.lastname: Zhu
authors.forename: Guoxiang
authors.initials: G
authors.lastname: Huang
mesh_terms: D003198:Computer Simulation; D008027:Light; D008029:Lighting / Q000379:methods*; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman / Q000379:methods*